Most recent record MS SQL

Question

Need only the most recent record

Current Data:

RequestID   RequestCreateDate         VehID    DeviceNum   ProgramStatus   InvID
1           08/12/2018 13:00:00:212     110       20178      Submitted        A1
2           08/11/2018 11:12:33:322     110       20178      Pending          A1
3           09/08/2018  4:14:28:132     110       Null       Cancelled        A1
4           11/11/2019 10:12:00:123     188       21343      Open             B3
5           12/02/2019 06:15:00:321     188       21343      Submitted        B3

Req Result:

RequestID   RequestCreateDate         VehID    DeviceNum   ProgramStatus   InvID 
3           09/08/2018  4:14:28:132     110       Null       Cancelled        A1
5           12/02/2019 06:15:00:321     188       21343      Submitted        B3

InvID is from tableB that I am joining.

Here is the query that I am currently trying but there are duplicate records:

Select 
    max(t1.RequestID) ReqID,
    max(t1.RequestCreateDate) NewDate,
    t1.VehID,
    t1.DeviceNum,
    t1.ProgramStatus,
    t2.InvID
FROM table1 t1
LEFT JOIN table2 t2 ON t1.VehID = t2.VehID
GROUP BY t1.VehID, t1.DeviceNum, t1.ProgramStatus, t2.InvID 

I need only the most recent record for each VehID. Thanks

Answer 1

On option is to filter with a subquery:

select t1.*, t2.invid
from table1
left join table2 t2 on t1.vehid = t1.vehid
where t1.requestCreateDate = (
    select max(t11.requestCreateDate)
    from table1 t11
    where t11.vehid = t1.vehid
)

For performance, consider an index on table1(vehid, requestCreateDate).

You can also use row_number():

select *
from (
    select t1.*, t2.invid, row_number() over(partition by vehid order by requestCreateDate desc) rn
    from table1
    left join table2 t2 on t1.vehid = t1.vehid
) t
where rn = 1